It's difficult to be patient in spring. Days are balmy and bright, and early flowers are popping into bloom. It's tempting to hurry summer along and begin planting warm-weather plants such as caladiums. But soil temperatures are still surprisingly cool, and these tropical natives prefer a cozier environment.

Planted too soon, caladiums will sit dormant in the damp, cold garden and may rot. Tucked under only a few inches of soil, they easily become damaged or lost in early-spring's gardening frenzy. To prevent these pitfalls and to get a jump on the season, start your tubers indoors. It's easy to do, and you'll protect your investment in this heat-loving foliage plant.

Step 1: Cut a piece of screen to fit the flat's bottom and halfway up the sides. Fill the container with moist potting soil about 1 inch deep.

Step 2: Rest the tubers, buds up, on the soil. Place them closetogether, but not touching. Cover with additional soil, and put the flat in a warm location. Keep the soil damp but not soggy. In three to four weeks, after any danger of frost has passed, the caladiums will be in full leaf and ready to plant. Editor's tip: I place the flat on my warm driveway during the day and bring it indoors at night. If rainy days prevail, I put it on top of my clothes dryer, which also generates heat when in use.

Step 3: When leaves have emerged, slip your hand underneath the tubers, and lift them from the flat onto a piece of newspaper or a worktable. Gently pull them apart, and plant in the garden or containers. Caladiums need only a few inches of soil cover, so don't bury them too deep.

What's Up?One of gardening's great mysteries is which side of a caladium tuber is the top. The nubby, irregularly shaped tuber gives few clues to this planting dilemma, and many times leaves you wondering if it will grow. The only hints I can give are these.

Look closely at one of the broad, flat sides. Run your finger lightly over the surface, feeling for tiny points which are new leaf sprouts. If you don't find any, turn it over and check the other side. These raised tips mark the top.

If that doesn't work, check for remnants of roots. They may be dehydrated and pressed against the surface of the tuber, but they will indicate the bottom.

When all else fails, plant the caladium on its side. The tuber will sprout, and you won't have to worry about it. Even if you do plant upside-down, chances are good the tuber will grow anyway--it may just take it a bit longer.